Looking Up: Hydra stretches across the sky
Daylight Savings Time - which occurs at 2 a.m. March 10 this year, brings us more of our beloved daytime star, the Sun, in the early evening hours. It also means we have to be a little more patient to see the REST of the stars, which appear an hour later than they had been.
It’s worth the wait, and as the nights shorten through the spring, we’ll just have to make the most of the abbreviated starry night.
Among the many highlights on a March evening is Hydra the Water Serpent, the longest and largest constellation in the sky.
The way the stars have been connected by the imagination of long ago astronomers, Hydra is a full 100 degrees long, from its “nose” in the western end to the tip of the “tail” on the far eastern end.
Remembering your high school geometry, a quarter of a circle is 90 degrees. From the flat horizon straight up to the zenith (overhead point) is 90 degrees. Hydra stretches further than that.
The celestial serpent moves “head-first” as the sky turns from east to west. The stars marking the “head” of Hydra are due south around 10:30 p.m., in mid-March. If you go out earlier, look in the southeast. As seen from mid-northern latitudes “head” stars reach about half way up in the southern sky.
There are six stars clustered together, making Hydra’s “head.” The rest of the constellation meanders down (south) and to the left (eastward).
Most of the stars are faint, and need a fairly dark sky without much moonlight. The Moon is a crescent in the western sky at this time, reaching First Quarter on March 14.
Hydra has one conspicuous star, however, about 20 degrees to the lower left of the “head.” Named Alphard, the star is noticeably orange in binoculars or a telescope. Alfred is magnitude 2.0, and is 177 light years away. A giant star, Alphard has a radius 50 times that of the Sun. The star appears on the flag of Brazil.
Around midnight in mid-March, the entire constellation stretches across the sky, formless in the southeast to high in the south-southwest. In mid-April you can look around 10 p.m.
Along the length of Hydra are a few smaller constellations, including the very dim Sextans the Sextant, dim Crater the Cup and the fairly bright stars of Corvus the Crow.
Hydra is very old, adapted by the ancient Greeks from a Babylonian constellation.
Keep looking up!
Peter Becker is Managing Editor at The News Eagle in Hawley, PA. Notes are welcome at firstname.lastname@example.org. Please mention in what newspaper or web site you read this column.